Basophil activation test (BAT) in wasp venom allergy during mastocytosis Dear Editor, A recent article by Bidad et al, evaluated the analytical performance of basophil activation test (BAT) in subjects with mastocytosis and wasp venom allergy (WVA), following venom immunotherapy (VIT) (1). The Authors reported an apparently excellent dose-related membrane upregulation of CD63 and CD203c markers and concluded that both molecules resulted reliable in diagnosing WVA in people affected by mastocytosis, as they showed comparable dose-response patterns (1). Yet, addressing possible bias should henceforth highlight the novelty of the issue Gating by CD45/IgE capture, on a FSC/SSC dot plot, may not prevent FcεRI-mediated cell spontaneous activation by polyclonal anti-IgE, as chilling samples does not hamper antibodies to react (2). Spontaneous activation caused also by pre-analytical issues (3), which the Authors did not address in their paper, may reduce the reliability of the reported results and not allow to construe them as an evidence of allergy; yet, pre-activated basophils may affect threshold sensitivity to different allergen doses (4,5). When Bidad and colleagues reported that median range values of CD63% and CD203c increase in a dose-response manner by challenging basophils with increasing doses of hymenoptera venom (0-5000 ng/ml) only in mastocytosis affected subjects with wasp venom allergy (Figure 2 in ref 1), the reader wonder why they did not introduced a similar doserelated curve for WVA subjects without mastocytosis, to assess BAT reliability, due to the complex relationship between mastocytosis and hymenoptera allergy (6). One criticism about the reliationship between WVA and mastocytosis deals with non-IgE mediated allergy, for example during mastocytosis anaphylactic reactions are more frequently due to non IgE-mediated reactions (7,8). Several reports exist showing patients with mastocytosis and a history of severe sting reactions, but in whom venom-specific serum IgE was absent (9,10) or who additionally had also negative venom skin tests (11,12). Further evidence showed individual patients with cutaneous mastocytosis, venom sensitization, which could not be demonstrated by routine methods (13). Such issues might stimulate the hypothesis that patients with mastocytosis and systemic sting reactions would actually not suffer from true WVA (14), but demonstrate a pseudo-allergy, although several author since the 1990 including a large European multicentre study has clearly shown the allergic link between mastocytosis and insect venom anaphylaxis (15). All these considerations, should ask

This article has been accepted for publication and undergone full peer review but has not been through the copyediting, typesetting, pagination and proofreading process which may lead to differences between this version and the Version of Record. Please cite this article as an ‘Accepted Article’, doi: 10.1002/cytob.21182

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for a better dissection between WVA and mastocytosis, when BAT reliability and performance is investigated. Moreover, CD63+ percentages mainly rely on which CD63 expression cut off is determined. Bidad and colleagues did not show any CD63+ percentage increase in basophils from non WVA subjects (1), indirectly suggesting that in mastocytosis affected patients hymenoptera venom did not elicit any CD63 up-regulation response, despite previously reported papers (16). CD63 cut off values in Bidad’s paper may depend on the unbalanced ratio between WVA and non WVA individuals, as non WVA subjects included in CD63 cut off evaluation accounted for at least one third of the recruited subjects (1). The conclusion reached by Bidad and colleagues, about BAT performance, should have taken into account these facts and observations and include them in the discussion, in order to expand the debate on BAT performance.

The Author states he has no conflict of interest

Salvatore Chirumbolo, Ph.D. Department of Medicine University of Verona, Italy LURM-Est Policlinico GB Rossi Piazzale AL Scuro 10 37134 Verona (Italy) Tel. +390458128456 Fax +390458027403 e-mail: [email protected]

LITERATURE CITED 1.

Bidad K, Nawijn MC, van Oosterhout AJ, van der Heide S, Oude Elberink JN. Basophil activation test in the diagnosis and monitoring of mastocytosis patients with wasp venom allergy on immunotherapy. Cytometry B Clin Cytom. 2014 Jan 29, in press DOI: 10.1002/cyto.b.21148

2.

Chirumbolo S. Basophil activation test in allergy: time for an update? Int Arch Allergy Immunol. 2012;158(2):99-114

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Sturm EM, Kranzelbinder B, Heinemann A, Groselj-Strele A, Aberer W, Sturm GJ. CD203cbased basophil activation test in allergy diagnosis: characteristics and differences to CD63 upregulation. Cytometry B Clin Cytom. 2010 Sep;78(5):308-18

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Macglashan D Jr. IgE and Fc{epsilon}RI regulation. Ann N Y Acad Sci. 2005 Jun;1050:73-88

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Sihra BS, Kon OM, Grant JA, Kay AB. Expression of high-affinity IgE receptors (Fc epsilon RI) on peripheral blood basophils, monocytes, and eosinophils in atopic and nonatopic subjects: relationship to total serum IgE concentrations. J Allergy Clin Immunol. 1997 May;99(5):699706

6.

Bonadonna P, Zanotti R, Melioli G, Antonini F, Romano I, Lenzi L, Caruso B, Passalacqua G. The role of basophil activation test in special populations with mastocytosis and reactions to hymenoptera sting. Allergy. 2012 Jul;67(7):962-5

7.

Oude Elberink JNK, de Monchy JGR, Kors JW, et al. Fatal anaphylaxis after a yellow jacket sting, despite venom immunotherapy, in two patients with mastocytosis. J Allergy Clin Immunol 1997; 99:153–161.

8.

Haeberli G, Bronnimann M, Hunziker T, Muller U. Elevated basal serum tryptase and hymenoptera venom allergy: relation to severity of sting reactions and to safety and efficacy of venom immunotherapy. Clin Exp Allergy 2003; 33:1216–1220.

9.

Müller UR, Horat W, Wu¨ thrich B, et al. Anaphylaxis after Hymenoptera stings in three patients with urticaria pigmentosa. J Allergy Clin Immunol 1983; 72:685–689.

10. Bucher B, Simic P, Furrer J, Wu¨ thrich B. Mastocytosis: an important differential diagnosis in anaphylactoid reaction to Hymenoptera sting. A case report and overview of clinical aspects, diagnosis and current therapy of mastocytosis. Schweiz Rundsch Med Prax 2000; 89:411–418. 11. Florian S, Krauth MT, Simonitsch-Klupp I, et al. Indolent systemic mastocytosis with elevated serum tryptase, absence of skin lesions, and recurrent severe anaphylactoid episodes. Int Arch Allergy Immunol 2005; 136:273–280. 12. Kränke B, Sturm G, Aberer W. Negative venom skin test results and mastocytosis. J Allergy Clin Immunol 2004; 113:180–181. 13. Fricker M, Helbling A, Schwartz L, Mu¨ ller U. Hymenoptera sting anaphylaxis and urticaria pigmentosa: clinical findings and results of venom immunotherapy in ten patients. J Allergy Clin Immunol 1997; 100:11–15. 14. Ruëff F, Placzek M, Przybilla B. Mastocytosis and Hymenoptera venom allergy. Curr Opin Allergy Clin Immunol. 2006 Aug;6(4):284-8 15. Ruëff F, Przybilla B, Biló MB, Müller U, Scheipl F, Seitz MJ, Aberer W, Bodzenta-Lukaszyk A, Bonifazi F, Campi P, Darsow U, Haeberli G, Hawranek T, Küchenhoff H, Lang R, Quercia 3

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O, Reider N, Schmid-Grendelmeier P, Severino M, Sturm GJ, Treudler R, Wüthrich B. Clinical effectiveness of hymenoptera venom immunotherapy: a prospective observational multicenter study of the European academy of allergology and clinical immunology interest group on insect venom hypersensitivity. PLoS One. 2013 May 20;8(5):e63233 16. González-de-Olano D, Alvarez-Twose I, Morgado JM, Esteban López MI, Vega Castro A, Díaz de Durana MD, Sánchez-Muñoz L, Matito A, de la Hoz Caballer B, Sanz ML, Orfao A, Escribano L. Evaluation of basophil activation in mastocytosis with Hymenoptera venom anaphylaxis. Cytometry B Clin Cytom. 2011 May;80(3):167-75

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